Method of making turbine blades



y 1953 K. M. BARTLETT ET AL 2,638,663

METHOD OF MAKING TURBINE BLADES Filed Oct. 25, 1948 Patented May 19, 1953 METHOD OF MAKING TURBINE BLADES Kenneth M. Bartlett and Nicholas J. Connavino, South Euclid, Ohio, assignors to Thompson Products, Inc., Cleveland, Ohio, a. corporation of Ohio Application October 23, 1948, Serial No. 56,184

2 Claims.

This invention deals with the production of blades for turbines and compressors of steam turbine or gas turbine engines such as turbo-j engines and jet-propulsion engines.

Specifically the invention relates to the production of turbine and compressor blades from bar stock having a cross-sectional contour in the shape of an air foil, the stock being formed at one end into a butt or root designed for attachment to a rotor hub or stator ring.

It is an object of this invention to provide a method whereby turbine and compressor blades may be formed from bar stock.

Another object of this invention is to provide a method whereby the tip of a piece of bar stock may be gathered into the form of a butt or root for attachment to a turbine engine part.

A further object of this invention is to provide a method whereby elongated bar stock may be given an air foil cross-sectional contour, cut into blade lengths, upset at one end to form an anchoring root, and cambered into the proper shape to act as a turbine or compressor blade.

Other and further objects of the invention will be apparent to those skilled in the art from the following detailed description of the annexed sheet of drawings which, by way of preferred example only, illustrate one embodiment of the invention.

On the drawings:

Figure l is a perspective view of a piece of bar stock with a cross-sectional contour in the shape of an air foil;

Figure 2 is a perspective View of a section of bar stock similar to Figure 1 except that the sides have been cut away from one end to leave a reduced width tang;

Figure 2A is an end view showing how the tang can be flattened if desired.

Figure 3 is a view, partially in cross-section, of an electric upsetting machine forming an upset head from the tang end of the member shown in Figure 1;

Figure 4 is an enlarged fragmentary view, partially in cross-section, showing a die shaping of a fillet portion on the upset head formed on the member;

Figure 5 is a perspective view showing the shape of the upset member after the end thereof has been die shaped into a compact mass;

Figure 6 is a top plan view showing the member of Figure 5 after machining operations on the root have been completed; and

Figure '7 is a side elevational view showing the twisted blade portion of the member formed according to the invention to give a desired camber to the vane portion of the member.

As shown on the drawings:

In Figure 1, a cut length of bar stock ID has a transverse air foil contour l with a concave face Ila and a convex face I lb. Elongated bar stock of rectangular cross-section may be shaped to form such an air foil, by rolling, forging, machining etc., and pieces [0 of desired length are conveniently cut therefrom.

In order that the stock may serve as a turbine or compressor blade it is necessary to twist the blade portion to provide the proper camber for the anticipated operating conditions. It is also necessary to provide an enlarged root or butt on one end of the blade for anchoring the blade to a stator or rotor. Since considerable stress is applied to the blade at the hub portion thereof, a strong anchor must be provided.

According to this invention, the first step in forming a butt is to cut away the leading and trailing edges of the airfoil at one end of the stock in order to provide a tang l2 of reduced width. This tang I 2 has tapered shoulders In with rounded ends merging into the longitudinal sides of the air foil and tang. If desired, the tang [2 can be flattened, as shown in Figure 2A, to a uniform thickness. This reduced width tang portion and shoulder arrangement forms a section which can be headed and shaped to form a desired root shape and fillet between the root and vane portions of the blade.

After the tang I2 has been cut, the stock is placed in an electrode l3 (Figure 3) of an electric upsetting machine with the tang portion thereof extending toward an electrode [4. The electrode l3 has a contoured aperture |3a shaped to slidably contact the airfoil shape of the barstock 10. If desired, the electrode can be in two sections with a bottom section having a top contour to fit the face Ha or Nb of the piece I0, and a top section having a bottom face shaped to fit the opposite face of the piece. The electrode I4 is carried by a piston l5 which is slidable in a cylinder I6. Fluid in the cylinder It will be relieved whenever axial pressure on the electrode l4 exceeds a predetermined amount so that the electrode will not be overloaded. A pusher l1 acts on the bar piece [0 to slide it through the electrode l3 to force the tang end l2 against the electrode IA.

The electrodes l3 and M are in a low voltage, high amperage electric circuit which is closed when the piece l0 isin the electrode l3 and the tang 12 contacts the electrode [-4. The electric airfoil contour of the piece It isthrough free bend fillets along the length. of thehead Hibetween the head and each face Hit or i lb, it. is.

desirable to control the contour: of; the fillets by a coining operation shown in Figure 4 in order to obtain the most efficient reinforcement contour which will not interfere with the emciency of the airfoil. Thus while thehead. I 8:

is still in a heated forgeable state, the piece 19 is; placed. in coiningv dies I9, I9 having rounded active faces |9a,. 19a. for receiving the fillet portion of the head is. A plunger 2.9, then. presses the head l9. toward. the dies to conform. fillet con-tours 19a in conformity with the. shape of the: die faces 19a. These fillets 18c blend the head. into. the airfoil section. so that, no sharp edges or. crackswill develop. In, addition, sufficient. reinforcing metal isprovided at these points to insure a smooth blending of the concavo-oonvex, airfoil with. the thickened cylindrical'head l8.

If desired, thecoining of. Figure l, can be carried: out on the; upsetting machine. of. Figure 3 by forming the faces. 1.911 on the electrode 13.

As shown in. Figure 5, the upset. and coined piece it. has its original airfoil. H for the major portion ofits. length, and an. integral thickened cylindrical head If of reduced width is blended into, one end of the airfoil, section. by contoured fillets l-fia.

tang. t2, shown. in Figure-2A,. givesbetter. control ofthehead. shape, but this. flattening step is not always. necessary.

A finished blade 2.l-, shown inEigures 6 and. 7, is-formed. from. the headed, piece. [9' of; Figure 5 by coining the airfoil body H. of the piece along. its. length. to; form a. twisted vane portion. 21ahaving the, original concave face, Mia. and convexv face M11. twist provides thedesiredcamber or pitch in the vane 21a. machined to form. the finisheclroot or butt. 21b for. the. blade. As shown in Figure 7, the fillets ifia. blend the root 2312 into the vane 2la, and! strengthen. the blade ata pointv which, in use is subjected-to great stresses.

Iirom theahove descriptions it should be clear that, the invention provides blades for turbine engines and: the like from, inexpensive contoured bar stock. by inexpensive trimming, upsetting, and coining; operations.

We claim as our invention:

1i. The method of producing a blade for turbines and the like which: comprises, providing;

elongated; bar stock havinga thick longitudinal central portion, thin longitudinal leading and;

tr iling lse-s, a: o cav fr nt facea-nd a: Q0111 vex; back. face, cutti11&;said has sta k. nt p eces.

The ends of the head. 18 are. joined. with the leading and trailing. ends of. theairfoil.

The head. [8. is.-

4 of slightly greater length than the length of the desired blade, trimming off the leading and trailing longitudinal edges of one end of the thus cut length along concave paths from said edges to the thick central portion and thence along lines parallel with said edges to produce a generally rectangular tang on" said one end of reduced width. composed only of the thick central portion of the bar stock and merging into said leading and trailing longitudinal edges along smoothly rounded edges, flattening said tang to forma section of uniform thickness, heating the tang, to. forging temperature, upsetting the heated tang to;- reduce the longitudinal length thereof While. increasing the thickness thereof to form a headblended into the concave and convex faces through free bend fillets along the juncture of' said head and faces, and coining said. filletsq into rounded concave shapes which will not interfere with the airfoil efiiciency of said faces to provide an anchoring root portion of; less width. and. greater thickness than the bar stock and blended into both the faces and the edges of the bar stock along smooth rounded concave surfaces.

2. In the method of producing a blade for turbines. and the like frombar. stock having a thick longitudinal central portion, thin longitudinal leading and trailing edges, a concave front face and a convex back face, the steps which comprise trimming. 0a the leading and trailing longitudinal edges at one end of the bar stock along concave paths from said edges to the thick longitudinal central portion of the bar stock and thence along lines parallelwith said edges thereby producing a, generally rectangular tang on said end ofv reduced width composed only of the thick central portion of the bar stock and merging into said leading. and trailing longitudinal edges along. smooth rounded edges, flattening said. tang to form a section of uniform thickness, heating, the tang to forgin v temperatures, upsetting the heated. tang to reduce the longitudinal. length, thereof while increasing the Y thickness thereof. to form a head blended into the. concave and, convex faces through free bend fillets. along. the juncture of said head andfaces and blended. into-the leading and. trailing edges along tapered shoulders formed from the concave trimmed portions, coining. the free bend fillets into rounded concave shapes merging into the concave front faceand convex back face of the bar stock, and machining the thus formed coined head. to provide an anchoring root for the blade. having less. width and greater thickness than the bar stock. and blended into both the faces and the edges of the bar stock. along smooth surfacesfree from .folds.

KENNETH M. BARTLETT. NICHOLAS J. CONNAVINO.

References Cited in the file of this patent UNITED. STATES PATENTS Number Name Date 883,889" Kisser Apr. 7, 1908 1,430,399 Parsons Sept. 26, 1922 1 ,891,612 Schmidt Dec. 20, 1932 1;.9473347 Lorenzen Feb. 13, 1934 2,063,706 Soderberg Dec. 8, 1935 2,355,413 Bloomberg Aug. 8; 1944 $412,615 Howard Dec. 17, 1946 2,459,850 Stine: Jan. 25, 1949 2,473,245 Hanna June. 14, 1949 2.503.630. Norton l, l. Apr. 11;, 1950; 

